Recently, due to depletion of fossil energy and environmental pollution caused by using fossil energy, interest in electrical products capable of being driven by using a secondary battery has increased. As a result, as technical development and demand for a mobile device, an electric vehicle (EV), a hybrid vehicle (HV), an energy storage system (ESS), an uninterruptible power supply (UPS), and the like, demand of the secondary battery as an energy source has been rapidly increased.
The secondary batteries have received attention as a new energy source for environment-friendly and improvement of energy efficiency in that no by-product is generated depending on use of energy in addition to a primary advantage of remarkably reducing use of fossil energy. Particularly, the second battery which is used for the EV, the HV, the ESS, or the UPS uses a battery pack in which a plurality of battery modules is connected to each other as a power source in order to charge or discharge high-output and large-capacity power.
As such, in the battery pack in which the high-output and large-capacity power is frequently charged or discharged, various switch elements such as an on/off switch for controlling charge and discharge of the battery pack and a relay switch for protecting the battery pack from overcharging, over-discharging, and a surge current are installed to control and protect the battery pack.
In the switch element installed in the battery pack, due to deterioration in which physical performance deteriorates by operating the battery pack, a turn-on resistance value of the switch element is increased and thus a control function and a protection function of the battery pack of the switch element are lost by accelerating the deterioration of the switch element.
Accordingly, when the battery pack operates, it is important to detect the deterioration of the switch element installed in the battery pack and it is very important to exactly calculate the turn-on resistance of the switch element in order to more exactly detect the deterioration of the switch element.
A technique of detecting the deterioration of the switch element installed on the battery pack in the related art monitors a temperature of the switch element through a temperature sensor at all times to compare a measured temperature and a reference temperature by a comparing apparatus and determines that the switch deteriorates when the measured temperature of the switch element is more than the reference temperature. However, the temperature of the switch element, as a temperature influenced by an internal temperature of a housing in which a plurality of switches, a protection circuit, a control module, and the like are received, is a temperature which is changed according to a temperature of a switch surface, that is, a periphery environment of the switch, not a temperature of the switch itself.
Accordingly, since the technique of detecting the deterioration of the switch element by measuring the temperature of the switch element uses the temperature influenced by the ambient environment of the switch, reliability and precision of the detected result deteriorate.
As a result, in order to solve the aforementioned problems in the related art, the inventors of the present invention invented switch deterioration detection device and method, which include a resistor which is serially connected with a battery of which charge and discharge are controlled by switch, compare an output voltage amplifying a voltage difference between both ends of the switch and an output voltage amplifying a voltage difference between both ends of the resistor, by the comparator to detect deterioration of the switch, and control at least one of a resistance value of the resistor, an amplification ratio of a differential amplifier amplifying a voltage difference between both ends of the switch, and an amplification ratio of a differential amplifier amplifying a voltage difference between both ends of the resistor so that output voltages of the differential amplifiers are the same as each other and calculate a turn-on resistance value of the switch by using the resistance value of the resistor and the amplification ratio of the differential amplifier at the time when the output voltages are the same as each other.